Hitherto, it has been found difficult to machine enlargements of metallic workpieces having thin portions interconnecting such enlargements or projecting from a single enlargement without causing undesirable deformation of the thin portion. Prior attempts to prevent such deformation have included casting a molten matrix material around the thin portion between the thick portions, after which the machining of the thick end portions was carried out, whereupon the matrix material is melted away from the thin portion of the workpiece. This procedure, however, has added considerably to the expense of producing such workpieces and has resulted in heavy expenditure of time and frequent distortion of the workpiece notwithstanding this attempted prevention. This problem has been particularly acute in the machining of the enlarged opposite end portions or of the single end enlargement of a jet engine blade, the airfoil section between the thicker opposite ends or projecting from the single enlarged end being considerably thinner and therefore subject to undesired deformation during machining of the opposite end enlargements or of the single end enlargement, as the type of blade may be.